1. Field of the Invention
Cytotropic Heterogeneous Molecular Lipids (CHML) penetrate through target cancerous cells to perform programmed cancer cell death (cancer apoptosis). Furthermore, CHML has produced anti-cancer angiogenesis and induced immune function increase.
2. Description of the Related Art
Phosphatide has been known to form small multilayered capsules while dispersing in water, and discovered that each layer of bimolecular lipids in a multilayer cyst is separated by water, the thickness of each layer being about 40 Å. This kind of capsule formed of microparticles, having a structure similar to a biomembrane, is termed a liposome.
Since liposomes form a hydrophilic and/or lipophilic container-like structures, these structures may envelop molecules and ions which are soluble in water or lipid. Due to these specific characteristics, liposomes can be useful as carriers, especially for pharmaceuticals. Further, liposomes may alter the mechanism of pharmaceutical metabolism and selectively transport the pharmaceutical to the “target”, then release the pharmaceutical at the proper part of tissues to be cured. Thus, toxicity to normal cells can be reduced and the curative effect, i.e. attack on deleterious cells, can be greatly enhanced.
In addition, there is another specific property in that the pharmaceutical enveloped by the liposome may be slowly released into local sites whether entering into blood circulation or combining with cells and tissues, even entering into cells through pinocytosis. With the slow release mechanism of liposomes, the half-life of the effective pharmaceutical is prolonged and the therapeutic effect is obviously improved. Furthermore, liposomes are made from natural phosphatides and cholesterols, having low toxicity, free from immunogens and with suitable bio-compatibility and bio-degradable properties.
In the related art, liposomes have been formed from phosphatide as a skeleton material and additives. Phosphatide is an amphoteric compound possessing hydrophilic and lipophilic radicals, including natural phosphatide (lecithin and soy-bean lecithin) and synthetic phosphatide (such as phosphalidyl choline, dipalmitol phosphatidyl choline and distearyl phosphatidyl choline). These phosphatides provide two hydrophilic chains. They form liposomes of bimolecular layers in water, no matter how the structure of the hydrophilic radical is. The additives used have been, for example, cholesterol, octadecamine and phosphatidate, etc. Although cholesterol is useful for regulating the flowability and permeability of a bimolecular layer, cholesterol is not healthy for human beings. Octadecamine and phosphatidate may be used to alter the surface electrical charges of a liposome. The components of a polythase liposome may be phosphatide, oleic acid, cholesterol and nonionic surfactants such as PVP (polyvinyl pyrrolidone).
Liposomes are known as drug carriers, as models of bio-membranes, and methods of preparation. Polyphase liposomes are formed after the phosphatides contact with water. Formation is due to the action if its polar group and hydrophobic group which lead to the formation of poly bimolecular layers of a closed type spherical structure. The water layer is laid between the bimolecular layers as the water-soluble drugs are enveloped into it, the liposoluble pharmaceutical being enveloped in the bimolecular layers. Many factors as surface characteristics, particle sizes, differences in forms, surface electrical charges of the liposome can effect the stability in vivo and the percentages of enveloped pharmaceutical. The factors depend upon the components of phosphatides and methods of preparation.
However, the chemical properties of phosphatide with unsaturated fatty acid chain, such as of lecithin and soya bean lecithin, are prone to displaying insufficient stability. Phosphatide is susceptible to oxidation and hydrolysis. Thus, peroxides such as propanediol and lysophosphatide are produced. The oxidation of lecithin will subject the membrane formed to decreased flowability and increased stability and negative electrical charge conditions. Thus leakage of drugs will be promoted so that retaining of drugs will become less and the liposome will be easily aggregated and precipitated, thereby producing toxicity. Therefore, it would be advantageous if lecithin used as a membrane material should have high purity and an oxidation index of less than 0.2.
In the preparation of liposomes, it is a difficult problem to envelope a large quantity of drug. For example, where the liposolubility and aqueous solubility of the pharmaceutical are both low, the envelopment quantity of the drug will be less. Also, when the molecule of the drug is small and easily subject to percolation, the envelopment quantity of the drug will be weaker. As a result, conventional art liposome technology has been found to lack sufficient stability to deliver substances associated with rigorous therapeutic regimens. Particularly, suitable vehicles for carrying, cancer-fighting drug molecules are greatly desired.
Presently, acceptable medical treatment for different forms of cancer includes: surgery, chemotherapy, radiation and biological therapies. Recent advances in biotechnology have led to an improved understanding of the different biological functions that control the proliferation of malignant cells and the particular genetic defects which can lead to tumor growth.
Chemotherapeutic drugs are intended to destroy cancer cells, but are largely non-selective in their eradication of the body's cells. Research is currently focusing on drugs that are able to selectively kill cancer cells, which exhibits less toxicity to normal cells.
As a result, liposome technology offers advanced technology that can be used to create new cancer therapies.